1. Field of the Invention
The present invention relates to a proportioning valve system in the hydraulic brake system of a vehicle which includes a fixed ratio proportioning valve and a load sensor which enables the weight over the rear wheels to be measured for modifying the braking pressure applied to the front and rear wheel brakes in response to the load over the rear wheels.
2. Information Disclosure Statement
In the development of braking systems for passenger cars, many efforts have been made to modify the pressure available at the rear brakes upon depression of the brake pedal. The efforts to modify the braking pressure available at the rear brakes includes fixed ratio proportioning valves as well as height sensing valves in which the pressure is modified according to the height of the vehicle. The fixed ratio proportioning valves are somewhat limited in their application because of the variability in weight distribution of many passenger cars which causes excessive trade offs in the compromise to determine the best ratio. The height sensing valves attempt to remedy this problem but the system costs increase due to the necessary adjustments that are required at installation with these adjustments also being susceptible to inaccuracies and poor workmanship. The following U.S. patents disclose some of the attempts to modify the brake pressure available at the rear brakes of a passenger car or the like.
______________________________________ 3,162,491 Dec. 22, 1964 3,463,556 Aug. 26, 1969 4,062,597 Dec. 13, 1977 4,150,855 April 24, 1979 4,325,581 April 20, 1982 4,453,779 June 12, 1984 ______________________________________